The present invention relates to a method and to a machine for working a blade sector.
In the field of motors in general and in the aeronautic field in particular, it is known to use turbines which usually include a plurality of blade discs, each of which defines its own axis and is constituted by a plurality of blade sectors arranged alongside each other. Each blade sector includes a plurality of radial blades and, usually, two circular end bodies interconnecting opposite end portions of the blades themselves.
The working of each blade sector includes the finishing of the outer lateral surfaces of the said circular bodies and is currently effected with the use of machines each including a cutting head supporting a respective disc tool, generally a grinding wheel, and a worktable rotatable about its own axis.
In known machine tools, the tables are dimensioned so as to support and retain a plurality of blade sectors which are arranged on the table close together in an array so as to form a ring or half-ring of the blade sectors on an axis coincident with the axis of the table. At this point, the outer surface is worked by positioning the disc tool with its cutting surface in contact with the outer surface to be worked and simply rotating the table about its axis.
The method of working just explained, although used, has a major disadvantage of rendering the working large bladed sectors extremely difficult if not impossible. In fact, the positioning of the bladed sectors in the said array on the table necessarily involves the use of large-diameter tables with the result that the machine itself is very bulky.
Moreover the various sectors on the table must be mounted on the table extremely precisely and this necessitates not only rather long assembly times but also the use of relatively complex and expensive positioning equipment.
Finally, the method just explained is not very satisfactory in that any geometric and/or dimensional error made during the mounting of the sectors on the table or during the working of the sectors themselves results in the waste of all the sectors present on the table with very considerable losses both in terms of production and of material used.